Almost 45% of the United States population is fully vaccinated, according to figures from the Centers for Disease Control and Prevention.
In recent weeks, the alpha variant, the first time detected in the United Kingdom, has ceased to be the predominant one in that country and it is delta that accounts for most of the new infections reported.
The CDC warns that something similar could happen in the United States in the coming days.
However, vaccines appear to be effective against this variant, so unvaccinated people are most at risk.
